Detent mechanism for securing a knob to a door latch



May 28, 1963 M. E. WILLIAMS 3,091,490

DETENT MECHANISM FOR SECURING A KNOB TO A DOOR LATCH Filed Aug. 8, 1960FIG.

MURRAY E. WILLIAMS INVENTOR.

BY (B. fi/l ig United States Patent Ofifice 3,091,490 Patented May 28,1963 3,091,490 DETENT MECHANISM FOR SECURING A KNOB TO A DOOR LATCHMurray E. Williams, Grand Rapids, Micln, assignor to Dexter Industries,Inc., Grand Rapids, Mich, a corporation of Michigan Filed Aug. 8, 1960,Ser. No. 48,156 2 Claims. (Cl. 292352) This invention relates to theconstruction of door latches, and particularly to the mechanism fordetachably securing a knob to the tubular sleeve conventionally used totransfer torque fro-m the knob to the latch for retracting the bolt. Itis desirable that this detachable coupling should be engageable with asimple push-on movement, and should be disengageable without the use ofspecial tools other than that normally used for multiple purposes by aworkman. The knob, however, must not be disengageable under conditionsthat would provide unauthorized access to the interior of the latchmechanism.

It is conventional practice to secure a knob in position on a tubularsleeve through the action of a detent mounted for sliding movement withrespect to the sleeve in a direction corresponding to a diameter throughthe sleeve axis. This detent engages an opening in a cylindrical shankextending from the knob, and can usually be released by the manipulationof a screw driver in a manner such as to force the detent inwardly andout of the shank opening. An example of this type of mechanism is shownin Patent Number 2,694,309. This invention provides an improvement onthis type of structure, particularly with regard to the engagement ofthe knob with the detent on installation, and also with regard to themounting of the spring for biasing the detent to locking position. Theseveral features of the invention will be analyzed in detail through adiscussion of the particular embodiment illustrated in the accompanyingdrawing. In the drawing:

FIGURE 1 presents a fragmentary section in side elevation showing a knoblocked in engagement with a knob sleeve.

FIGURE 2 presents a perspective view showing a knob as it is firstinserted over the end of the knob sleeve, and prior to the engagementwith the retaining detent.

FIGURE 3 illustrates an intermediate position at which the detent isbeing retracted as the knob is progressively forced into thefully-engaged position shown in FIG- URE 1.

FIGURE 4 presents a plan view of the detent itself.

The knob sleeve is a tubular structure normally associated with aconventional door latch mechanism (the remainder of which is not shownin the drawing), and usually carries a pair of roll-back cams of thetype shown at 11 and 12 for operating the retractor mechanism of thelatch. The primary function of the sleeve 10 is to transfer themanually-supplied torque from the knob 13 to the latch mechanism whereit can be converted to forces exerted by the cams 11 and 12. Except forthe portions relating to the support and construction of the detent forretaining the knob 13 in position, the illustrated sleeve 10 isconventional in its construction.

The sleeve 10 is provided with a pair of diametrically opposite slots,one of these being shown at 14. These slots are parallel to a planeperpendicular to the axis of the sleeve 10, and receive the detent insliding engagement. If the amount of the desired sliding movement of thedetent 15 exceeds or approaches the thickness of the material of thesleeve 10, the material of the sleeve 10 adjacent to one or both of theslots 14 may be depressed radially inward with respect to the axis ofthe sleeve 10. The interior of the detent 15 is usually cutaway as shownat 16 to provide clearance for operating mechanism which may be confinedwithin the sleeve 10. The portions 17 and the projection 18 slide withinthe slots 14.

The locking projection 18 extends radially outward a sufficient amountto engage the opening 19 in the cylindrical shank 20 which is fixed withrespect to the knob 13. The opening 19 may be a pierced hole or anyconveniently-shaped discontinuity capable of receiving a portion of theprojection 18. The shoulders 21 and 22 abut the inside surface of thesleeve 10, and serve as a stop limiting the outward movement of thedetent 15 under the urging of the spring wire 23. An axial slot 24 isprovided in the sleeve 10 intersecting the slot 14, illustrated in thedrawing. This axial slot provides clearance for the deflection of thespring wire 23 during the movement of the detent 15. The spring wire 23is held in position through engagement with the loop 25 of materialpreferably lanced from the sleeve 10. On assembly, the spring wire 23 isinserted through the hole 26 in the detent 15, and through the loop 25.The loop may then be deformed somewhat to secure the spring in position.It is noteworthy that this construction permits the use of a completelystraight piece of steel wire for the spring 23', which requires nothingmore than a cut-oif operation in the manufacture of this component. Itis notorious that the tolerances in bending of spring steel wire arevery difiicult to maintain, and this arrangement eliminates a verytroublesome problem.

The knob shank 20 is provided with a preferably V-shaped notch 27axially opposite the opening 19. The surfaces 28 and 29' of the detent15 form an outwardlyconverging end to the projection 18, and cooperatewith the edges of the shank 20 which form the notch 27 to retract thedetent 15 as the knob is axially shoved into engagement with the sleeve10. As a result of the tapering conformation of the notch 27, theengagement of the sleeve 20 takes place with the surfaces 28 and 29,rather than with the exposed transverse face of the detent 15. FIGURE 3illustrates the result of this engagement, and the axial movement of theknob into the assembled position will result in retracting the detent 15inwardly to the point where it will slide underneath the shank 20 untilit can snap into engagement with the opening 19. This locked conditionis shown in FIGURE 1. Removal of the knob is accomplished by inserting ascrew driver at the opening 19 and engaging the end of the projection 18so that it can be pushed radially inward to the point where the knob canbe withdrawn.

The particular embodiments of the present invention which have beenillustrated and discussed herein are for illustrative purposes only andare not to be considered as a limitation upon the scope of the appendedclaims. In these claims, it is my intent to claim the entire inventiondisclosed herein, except as I am limited by the prior art.

I claim:

1. In a latch mechanism having a knob and a sleeve normally receivingsaid knob for transferring torque from said knob to said latch mechanismand supporting said knob, said sleeve having an axially-extending slotin the periphery thereof and an outwardly-extending oircumferentiallydisposed loop opposite the end of said slot, a system for detachablysecuring said knob to said sleeve comprising: a shank member normallyfixed with respect to said knob and engageable axially with said sleeve,said shank member having an opening in the wall thereof and a notchaxially aligned with said opening providing cam surfaces diverging toincreased width to the end of said shank; detent means slidably mountedin said sleeve for movement transversely to the axis of said sleeve at aposition intersecting said slot, said detent means having a hole andstop means limiting the outward movement thereof, and also having aprojecting portion of substantially uniform thickness tapening outwardlywith respect to said sleeve to reduced width in a plane normal to theaxis of said sleeve and receivable in said opening, said projectingtapering portion extending substantially radially from the periphery ofsaid sleeve for engagement with said cam surfaces in the position ofsaid detent determined by said stop means; and biasing means urging saiddetent toward said position, said biasing means including an initiallystraight piece of wire disposed adjacent said slot and engaging saiddetent hole and loop in said sleeve.

2. In a latch mechanism having a knob and a sleeve normally receivingsaid knob for transferring torque from said knob to said latchmechanism, a system for detachably securing said knob to said sleevecomprising: a shank member normally fixed with respect to said knob andengageable axially with said sleeve, said shank member having adiscontinuity in the wall thereof and a notch axially aligned with saiddiscontinuity providing cam surfaces diverging to increased width to theend of said shank; detent means slid-ably mounted in said sleeve formovement transversely to the axis of said sleeve and having a projectingportion of substantially uniform thickness tapering outwardly withrespect to said sleeve to reduced width in a plane normal to the axis ofsaid sleeve to define edges engageable with said cam surfaces andreceivable in said discontinuity; and biasing means urging said detenttoward engagement with said discontinuity.

References Cited in the file of this patent UNITED STATES PATENTS2,801,123 Kubik et a1 July 30, 1957 2,842,389 Muttart July 8, 19582,850,313 Check et al. Sept. 2, 1958

2. IN A LATCH MECHANISM HAVING A KNOB AND A SLEEVE NORMALLY RECEIVINGSAID KNOB FOR TRANSFERRING TORQUE FROM SAID KNOB TO SAID LATCHMECHANISM, A SYSTEM FOR DETACHABLY SECURING SAID KNOB TO SAID SLEEVECOMPRISING: A SHANK MEMBER NORMALLY FIXED WITH RESPECT TO SAID KNOB ANDENGAGEABLE AXIALLY WITH SAID SLEEVE, SAID SHANK MEMBER HAVING ADISCONTINUITY IN THE WALL THEREOF AND A NOTCH AXIALLY ALIGNED WITH SAIDDISCONTINUITY PROVIDING CAM SURFACES DIVERGING TO INCREASED WIDTH TO THEEND OF SAID SHANK; DETENT MEANS SLIDABLY MOUNTED IN SAID SLEEVE FORMOVEMENT TRANSVERSELY TO THE AXIS OF SAID SLEEVE AND HAVING A PROJECTINGPORTION OF SUBSTANTIALLY UNIFORM THICKNESS TAPERING OUTWARDLY WITHRESPECT TO SAID SLEEVE TO REDUCED WIDTH IN A PLANE NORMAL TO THE AXIS OFSAID SLEEVE TO DEFINE EDGES ENGAGEABLE WITH SAID CAM SURFACES ANDRECEIVABLE IN SAID DISCONTINUITY; AND BIASING MEANS URGING SAID DETENTTOWARD ENGAGEMENT WITH SAID DISCONTINUITY.